Electrical properties of Y2O3 high-κ gate dielectric on Si(001): The influence of postmetallization annealing

Abstract

In this work we report on the electrical properties of Y2O3 dielectrics grown on silicon (001) substrates at low oxygen background pressure by molecular beam epitaxy. Using metal-insulator-semiconductor capacitors, it is shown that as-grown samples are characterized by a large number of interface states coupled with insulator traps. Annealing in forming gas improves the electrical behavior of the samples, especially those grown at low temperatures, having typical interface state density of the order of 1012 cm−2 eV−1. Overall, the electrical response depends on the structural quality of the interfaces and especially on the presence of a uniform SiOx interfacial layer. The permittivity κ of the Y2O3 films was found to be rather low (κ∼9), which is attributed mainly to deviations from stoichiometry and the associated generation of oxygen deficiencies in the metal oxide.